Shoe insole

ABSTRACT

An insole providing cushioning and control of foot motion. The insole includes a base. A lateral border and a medial border cooperate to align and support the foot. The lateral border and medial border are firmer than the base.

The present application claims priority to U.S. Provisional applicationNo. 60/732,799 for SHOE INSOLE, filed Nov. 2, 2005, which application isincorporated herein in its entirety by this reference.

The present invention relates in general to an improved shoe insole andmore particularly to an insole for women adapted to provide improvedcushioning, support, and motion control.

BACKGROUND OF THE INVENTION

The human foot is a very complex biological mechanism. While standing,the feet carry a persons entire weight. While walking the load on a footat heel strike is typically about one and a half times a person's bodyweight. When running or carrying extra weight the loads on the foot mayexceed three times the body weight. The many bones, muscles, ligaments,and tendons of the foot function to absorb and dissipate the forces ofimpact, carry the weight of the body and other loads, and provide forcesfor propulsion. Properly designed shoe insoles can assist the foot inperforming these functions and protect the foot from injury.

To be practical for distribution to the general public, an insole mustbe able to provide benefit to the user population without requiringindividualized adjustment and fitting. Insoles can be optimized toaddress the needs of different portions of the user population. Forexample, insoles can be designed to accommodate the biomechanicaldifferences between men and women.

Biomechanically men and women are very similar in most respects. Theyshare basically the same human design, with the same number of bones,muscles, ligaments, and a torso that supports two upper and lower limbs.However, there are some biomechanical differences. The mostdistinguishing anatomical feature between men and women is the pelvis.To facilitate child birth, the pelvis of a woman is typically broaderand rounder than that of a man. As a result, in women the thigh bone orfemur approaches the knee at a greater angle than in men. This angle,called the quadriceps angle or Q-angle, is, on average, about 18 degreesin women compared to about 13 degrees in men. This angulation placesgreater stress at the knee joint of most women, making them morevulnerable to misalignment injuries, such as anterior cruciate ligamenttears at the knee, 4^(th) and 5^(th) metatarsal fractures, peronealtendonitis, iliotibial band syndrome, and other injuries. Because womenalso typically have narrower heels and lighter bone structure across thetri-planar axis of the foot, they are more susceptible to over useinjuries and compensatory injuries when trying to reduce stress alongthe medial aspect of the knee joint

Women compensate for a greater Q-angle by moving their center of masslaterally to the outside to place the leg in a straighter alignment overthe foot. Women also tend to pronate more than men because their footstrikes the ground in a more supinated position on the outside of theirfeet during foot strike.

In view of the foregoing, it would be desirable to provide anover-the-counter insole that provides cushioning adapted to thebiomechanics of women.

It would also be desirable to provide an insole that provides pronationcontrol adapted to the unique biomechanics of women.

SUMMARY OF THE INVENTION

The above, and other objects and advantages of the present are providedby an insole that provides both motion control and cushioning. Theinsole includes a system of interacting components that cooperate toachieve a desired combination of foot cushioning and motion control. Thecomponents include a base, a lateral and medial cradle, a heel plug, anda number of elastomeric pads. The characteristics of these components,their size and shape, and their position are selected to provide adesired blend of cushioning and control, and more specifically toachieve a desired biomechanical function.

In accordance with principles of the present invention, a cushioningbase is combined with firmer pads along the medial side, lateral side,and rear of the foot to form a cradle to support the foot whileproviding cushioning, stability, and control. Additional elastomericpads under the heel and forefoot provide additional cushioning. Byaltering the size, shape, and material properties of the pods insolesmay be designed to address issues related to foot motion.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, and other objects and advantages of the present inventionwill be understood upon consideration of the following detaileddescription taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

FIG. 1 is a exploded perspective view of an illustrative embodiment ofan insole in accordance with the principles of the present invention;

FIGS. 2 to 4 are, respectively, plantar (bottom), medial (inside), andlateral views of the insole of FIG. 1;

FIGS. 5 to 8 are transverse cross sectional views of the insole of FIG.2; and

FIG. 9 is a longitudinal cross sectional view of the insole of FIG. 2.

DETAILED DESCRIPTION

In reference to FIGS. 1 to 9, an insole constructed in accordance withthe principles of the present invention is disclosed. As shown in theexploded view of FIG. 1, insole 20 is a composite structure includingbase 22, cushioning pad 24, lateral border 26, medial border 28, heelplug 30, forefoot pad 32, and top sheet 34.

As shown in FIG. 1, base 22 generally has the shape of a partial insoleextending from behind the heel to the area of the forefoot. Base 22 ismade of a foam or other durable material having suitable cushioning andsupport properties. For example, base 22 is preferably made of apolyurethane foam of about 3 to 12 mm thick and having a durometer ofabout 49 to 53 Asker C.

Base 22 has a raised edge that wraps around the heel and extendspartially along the sides of the foot such that the insole conforms tothe natural shape of the foot. As best seen in FIGS. 5-9, the height ofthe raised edge is generally higher, and the base material is thicker,on the medial side of the foot and is lower on the lateral side. Base 22includes thicker portions in the shape of pods generally along acenterline of the foot. Base 22 further includes indented areas orregions designed to accept various pads and plugs as discussed below.

Cushioning pad 24 is disposed on the upper surface of base 22 andgenerally extends under the entire foot, from the heel to the toes.Cushioning pad is made of a softer cushioning material than base 22 tocontrol and distribute the initial impact of foot strike. For example,cushioning pad 24 is preferably a neoprene foam layer about 2 to 3 mmthick and having a durometer of about 21 Asker C.

An upper surface of cushioning pad 24 is covered with top sheet 34,which is preferably a non-woven fabric layer with a low coefficient offriction so as to minimize the possibility of blisters. The fabric istreated with an antibacterial agent, which in combination with amoisture barrier reduces odor causing bacteria and fungus. A series ofair ports extending through insole 20 permit air circulation above andbelow insole 20.

Lateral border 26 and medial border 28 cooperate to form a cradle thatgenerally extends from the heel through the midtarsal joints of thefoot. Lateral border 26 extends along the lateral side of the foot frombeside the calcaneous to the forefoot. Medial border 28 wraps aroundbehind a portion of the calcaneous and extends along the inside of thefoot through the arch to support and cushion the inside of the foot.Lateral cradle 26 and medial cradle 28 are made of a firmer materialthan base 22. For example, lateral cradle 26 and medial cradle 28 arepreferably made of a polyurethane material having a durometer in therange of about 60 to 70 Asker C. The use of pads or cushions made ofmaterials of differing density, or hardness, in conjunction with theshape and placement of the pads provides cushioning and control to helpcompensate for the increased Q-angle in women. The size, shape, andplacement of these pads are based on the location of various anatomicallandmarks of the foot and the biomechanics of foot motion.

As shown in FIGS. 5 to 9, lateral border 26 and medial border 28 wrap upthe sides and/or rear of base 22 to provide support for the foot. Thesides of stability medial border 28 are preferably higher than thelateral border because of the higher loading. For example, medial cradle28 extends upward under the medial longitudinal arch to providelongitudinal arch support.

Biological tissues such as tendons and ligaments are sensitive to therate at which they are loaded, the abrupt change in load may causeinjury or damage. Together, base 22, lateral border 26, and medialborder 28 function to place the female foot in better biomechanicalalignment with the leg and to balance their anatomical structure toreduce compensatory injuries. The medial arch support provided by base22 and medial border 28 slows down the rate of pronation and improvesbalance for the foot. The medial border 28 also cooperates with the rearportion of the lateral border 26 to provide added rearfoot stability.The lateral border 26 extends beyond the fifth metatarsal bone with acuboid support that functions to lock the midtarsal at midstance.

Forefoot pad 32 is positioned under the toes of the foot to providecushioning of the toes during toe off. For example, pad 32 may comprisea 1.5 mm layer of neoprene having a durometer of about 21 Asker C.

Gel heel plug 30 fits into a recess in base 22 and provides additionalcushioning at foot strike. Heel plug 30 preferably has a durometer ofabout 22 Asker C.

An upper surface of cushioning pad 24 is covered with top sheet 34,which is preferably a non-woven fabric layer with a low coefficient offriction so as to minimize the possibility of blisters. The fabric istreated with an antibacterial agent, which in combination with amoisture barrier reduces odor causing bacteria and fungus. A series ofair ports extend through top sheet 34, cushioning pad 24, and forefoodpad 32 to permit air circulation above and below insole 20.

While the present invention has been described in relation to preferredembodiments, the detailed description is not limiting of the inventionand other modifications will be obvious to one skilled in the art. Forexample, in the illustrative embodiment of the invention disclosed abovethe lateral and medial borders have the same firmness. However, over- orunder-pronation may be addressed by using a material of differentfirmness.

The present invention has been disclosed in the context of providing anover-the-counter insole that may be made available for distribution tothe general public. However, the same principles may be used by apodiatrist or other medical professional to design or create an insoleto address the needs of a specific patient.

Thus, an improved insole has been disclosed. It will be readily apparentthat the illustrative embodiment of an insole thus disclosed may beuseful in cushioning the foot and controlling pronation. However, onewill understand that the components of the insole system may be modifiedto achieve other ends. Thus, the description provided herein, includingthe presentation of specific thicknesses, materials, and properties ofthe insole components, is provided for purposes of illustration only andnot of limitation, and that the invention is limited only be theappended claims.

1. An insole for use in a shoe, the insole comprising: a core having ashape conforming to the inside of the shoe from the heel to theforefoot, the core having a top side and a bottom side; a lateral borderdisposed on the bottom lateral side of the core; and a medial borderdisposed on the bottom side of the core and extending from the lateralside of the heel.
 2. The insole of claim 1 further comprising: acushioning pad disposed on the top surface of the core and extendingforward of the core; and a forefoot pad disposed on the bottom of thecushioning pad and forward of the core.
 3. The insole of claim 1 furthercomprising a top sheet disposed over a top surface of the cushioningpad.
 4. The insole of claim 1 further comprising a heel plug disposed ina recess in the core.
 5. The insole of claim 2 wherein the lateralborder extends beyond the fifth metatarsal bone.
 6. The insole of claim1, wherein the firmness of the core is in the range of 49-53 Asker C. 7.The insole of claim 4, wherein the firmness of the lateral and medialborders are in the range of about 60-70 Asker C.
 8. The insole of claim5, further comprising a forefoot pad disposed forward of the base,wherein the firmness of the forefoot pad is in the range of about 16 to27 Asker C.
 9. The insole of claim 5, further comprising a gel heel plugdisposed in the base, wherein the firmness of the heel plug is in therange of about 16 to 27 Asker C.
 10. The insole of claim 1 wherein thelateral and medial borders fit within recesses in the base.
 11. Theinsole of claim 1, wherein the firmness of the base, the lateral border,and the medial border are selected to compensate for the greater Q-anglein women.
 12. An women's shoe insole, the insole comprising: a basehaving a shape conforming to the inside of the shoe from the heelthrough the mid-foot area; a first pad disposed in a first recess in thebottom of the base and extending along a lateral side of the base; asecond pad disposed in a second recess in the bottom of the base andextending from behind the heel along the medial side of the base throughthe longitudinal arch; a third pad disposed on a top surface of the baseand extending forward of the base; and a forth pad disposed under thethird pad and forward of the base.
 13. The insole of claim 12, whereinthe base comprises a material having a firmness of about 49 to 53 AskerC.
 14. The insole of claim 13, wherein the first and second padscomprise a material having a firmness of about 60 to 70 Asker C.
 15. Theinsole of claim 14, wherein the third pad comprises a material having afirmness of about 16 to 27 Asker C.
 16. The insole of claim 15, whereinthe forth pad comprises a material having a firmness of about 16 to 27Asker C.
 17. The insole of claim 12, further comprising a fifth paddisposed in a recess in the base under the heel.
 18. The insole of claim17, wherein the fifth pad comprises a material having a firmness ofabout 17 to 28 Asker C.
 19. A method of accommodating a larger Q-angle,the method comprising: providing a core having a shape conforming to theinside of the shoe and having a top side and a bottom side; providing alateral cradle disposed on the bottom lateral side of the core, thelateral cradle having a portion that extends beyond the fifth metatarsalbone; and providing a medial cradle disposed on the bottom medial sideof the core, the medial cradle extending from behind the calcaneousthrough the longitudinal arch; wherein the lateral and medial cradlesare firmer than the core.
 20. The method of claim 19, wherein the corecomprises a material having a firmness of about 49 to 53 Asker C and thelateral and medial cradles comprise a material having a firmness ofabout 60 to 70 Asker C.